A theatre in Scarborough has had to close parts of its building after it noticed a crack in concrete.
The YMCA Theatre said the crack was found in an inspection of the building prompted by reports reinforced autoclaved aerated concrete (RAAC) posed a safety risk in some schools.
The community theatre is based in a former school built in the 1960s.
Staff took the decision to close the majority of the building until it could be professionally inspected.
Liam Downey, general manager, said the team were being cautious: "We identified a part of our building that could contain RAAC concrete.
"This combined with the 1960s build date and the fact we are an old school raised alarm in our team.
"On closer inspection we noticed a crack in part of the concrete."
RAAC is a lightweight "bubbly" form of concrete used widely between the 1950s and mid-1990s - usually in the form of panels on flat roofs, as well as occasionally in pitched roofs, floors and walls.
Largely run by volunteers, the YMCA building in St Thomas St includes a 290-seat professional standard community theatre.
It is used by local arts groups, especially dance schools.
Mr Downey said theatre productions would still be able to go ahead, though the dressing rooms were out of action.